1. Field of the Invention
The present invention relates to a gas-discharge display device, and particularly to a structure for improving display quality of the panel (plasma display panel).
2. Description of the Background Art
FIG. 7 shows plane structure of a common AC-type plasma display panel (PDP).
The PDP forming the panel portion of a gas-discharge display device has a first substrate and a second substrate sealed at sealing portion at the edges with a sealing material formed of frit glass or the like, with a discharge space 22 filled with gas between the two substrates. A plurality of discharge cells are formed in a matrix in the discharge space 22. The discharge cells are individually controlled to discharge or not to discharge to cause phosphors 34 to emit light for display of desired picture.
The fist substrate has a front glass substrate (hereinafter referred to as an FP substrate) 10, on which sustain electrode lines (hereinafter referred to as X electrode lines) 12 and scan/sustain electrode lines (hereinafter referred to as Y electrode lines) 14 forming pairs of display electrode lines are formed like stripes. The X and Y electrode lines 12 and 14 are formed with three-layer structure of Ct/Cu/Cr by photolithography, or formed with Au by screen printing (also called thick-film printing). A dielectric layer 18 is formed almost all over the surface of the FP substrate 10 to cover the X electrode lines 12 and the Y electrode lines 14, and the dielectric layer 18 is covered by a discharge electrode layer 20 formed of MgO (also referred to as a discharge protection layer, hereinafter shown as an MgO layer), which serves as a cathode in discharge.
The second substrate has a rear glass substrate (hereinafter referred to as a BP substrate) 30, on which address electrode lines 32 are formed to extend in a direction perpendicular to the X and Y electrode lines 12 and 14. In the area corresponding to the display area of the PDP, red (R), green (G) and blue (B) phosphors 34 are correspondingly formed on the address electrode lines 32. Further, barrier portions (hereinafter referred to as ribs) 36 are formed by screen printing in intervals between the address electrode lines 32 to prevent optical cross-talk between adjacent address electrode lines 32, or between discharge cells.
The discharge cells are formed at intersections of the address electrode lines 32 and the X and Y electrode lines 12 and 14 extending perpendicular to the address electrode lines 32. Address pulses are applied to the address electrode lines 32, and at the same time, scanning pulses are applied to the Y electrode lines 14 to select discharge cells at the intersections. This causes the discharge cells to discharge (address write discharge) and accumulate wall charge. Subsequently, sustain pulses are applied alternatively to the Y electrode lines 14 and the X electrode lines 12 to produce sustain discharge between the Y electrode lines 14 and the X electrode lines 12 to sustain discharge. The phosphors 34 formed along the address electrode lines 32 are excited by ultra-violet rays produced by gas discharge in discharge cells and generate visible light.
While it is possible to display image by controlling the discharge cells as described above, it is desirable for the display device to make display with higher quality. Making display of good quality requires preventing reflection of external light to improve display contrast of discharge cells in the PDP and further improving the light emission efficiency at discharge cells.
However, it is also essential to reduce the manufacturing cost, while enabling display of good quality. For cost reduction, it is more advantageous to form the layers by screen printing than by thin-film process by photolithography. Accordingly, demanded is a PDP that can be stably formed by screen printing and provide superior display quality.